Between an uptick in droughts, increasing water pollution and a rising global population, access to clean drinking water is becoming a pressing issue for countless countries. The World Wildlife Foundation estimates that 1.1 billion people worldwide lack access to water and 2.7 billion experience water scarcity at least one month per year.
Many countries are turning to desalination in the hopes of addressing this growing water crisis. As the name suggests, desalination is a method of creating potable drinking water from one of Earth’s most plentiful resources: salt water. Over 97% of all water on the planet is salt water, and proponents point to desalination as the key to unlocking this massive natural reserve.
States have adopted a number of processes to purify salt water. The earliest technique — and the most rudimentary — is to simply evaporate salt water and collect the pure water vapor that is emitted. Nowadays, more than 80% of modern global desal plants use reverse osmosis to do the job. This process forces salt water through tiny openings in high-pressure tubs to separate salt particles from pure water.
Desalination has primarily been adopted by countries with severely limited access to fresh water. Israel, Saudi Arabia, the United Arab Emirates and Australia were all early adopters of the technology to stabilize drinking water supply in their desert climates. Small countries such as Singapore and Aruba have also increasingly adopted desalination to meet domestic drinking water demand and reduce their need to import water from other countries. Today, almost 20,000 desalination plants worldwide produce over 250,000 gallons of water daily.
The benefits from this increase is water production can have significant ripple effects beyond the plants themselves. Israel agreed to sell Jordan over 12 billion gallons of desalinated water in a diplomatic breakthrough last July. Israel can produce more water than it needs for the first time ever because of its significant investment in desalination — using this innovation to mend a long-fractured political relationship shows just how much of a game-changer desalination is.
Despite this hydro-political victory, desalination comes with major trade-offs. Powering desal is an incredibly energy-intensive operation. Many environmentalists are concerned that the increase in greenhouse gas emissions associated with the construction and operation of desalination plants will end up further contributing to climate change and water insecurity — and beget the need for even more desalination plants.
To the credit of desalination proponents, saltwater purification technology has become significantly more energy efficient over time. Contemporary reverse osmosis uses much less electricity to operate than the evaporative technique, and is now the gold standard in desal plants worldwide. Renewable energy also helps to mitigate the energy requirement of desalination. Countries are becoming more eco-conscious with desal. Singapore recently unveiled its first “dual mode’ desalination plant, capable of treating both sea water and fresh water from a nearby reservoir. The low salt content from the reservoir water also lowers the amount of energy required to operate the plant.
But beyond the energy costs lay even more pressing environmental costs. When drinking water is produced during desal, an extremely salty brine is left over as a toxic output. Desal plants often pump this brine back into the ocean, which California environmentalist Susan Jordan describes as “the blanket of death because it settles on the floor, and it kills everything.” For each gallon of potable water that a desal plant produces, a gallon of brine remains — a hazardous problem that could quickly get out of hand if countries continue to develop their desal programs.
Desalination is often out of reach for countries who need it the most. The price tag to build such facilities is high, costing almost double than traditional water infrastructure such as reservoirs and wastewater treatment plants. This is not to mention the higher operating cost of desal plants per gallon of water produced. Wealthy countries facing water insecurity such as Israel, Singapore and Australia can afford to foot the bill for these important systems while less developed countries facing similar shortages likely don’t have the cash or the technology to operate desal plants.
Perhaps one day technology will improve enough that countries can harness the sea to create an abundance of drinking water. For now however, desalination remains too expensive, too dirty and too energy intensive to be used as a long-term solution for water scarcity.
- Water stress: a global problem that’s getting worse — Council on Foreign Relations
- Towards sustainable desalination — United Nations Environment Program
- The role of desalination in an increasingly water-scarce world — World Bank